A study finds dozens of examples of migrants who were let go and later arrested, but the overall rate is far below that of the general prison population.

WASHINGTON — In January, Evin Adonis Ortiz was arrested and charged with killing a 24-year-old man in Los Angeles. After running Ortiz's fingerprints through an FBI database, police learned he was in the country illegally — and this wasn't his first arrest.

Ortiz had convictions for driving without a license and attempted grand larceny.

A congressional study released Tuesday found dozens of examples of illegal immigrants who were released and later arrested in connection with felonies, including murder.

The report, by the nonpartisan Congressional Research Service, studied the cases of 46,734 illegal immigrants. It concluded that those who had been arrested and released were later arrested in connection with 19 murders, three attempted murders and 142 sex crimes, among other infractions.

"President Obama's reckless amnesty agenda is dangerous and deadly for Americans," Rep. Lamar Smith (R-Texas), chairman of the House Judiciary Committee, said in a statement released Tuesday.

About 16% of illegal immigrants who were arrested were rearrested within three years, according to the study, which was based on data the Judiciary Committee had subpoenaed from the Obama administration.

That recidivism rate, however, is significantly lower than that of the general prison population. About 43% of prisoners released in 2004 nationwide were returned to prison within three years, according to a study by the Pew Center on the States, a nonprofit research institute. In California's state system, about 65% of released prisoners are back behind bars within three years.

The illegal immigrant rearrest rate is "pretty modest ... proportionally as compared with what happens in the criminal justice system in general," said Doris Meissner, a former head of the U.S. Immigration and Naturalization Service who is now a senior fellow at the Migration Policy Institute, a nonpartisan think tank.

U.S. Immigration and Customs Enforcementofficials noted that none of the people accused of murder in the report had been convicted. Ortiz has pleaded not guilty.

Ortiz, 22 when booked into jail, was charged in the slaying of Danilo Morales, who was shot in the head while trying to help his grandfather during a robbery outside a Sun Valley home.

The Obama administration, arguing that it is making the best use of a limited budget, has put convicted criminals and serial immigration violators at the front of the line for deportation.

But some Republicans argue that all arrested illegal immigrants should be deported.

"President Obama has imposed a policy that allows thousands of illegal immigrants to be released into our communities," said Smith, who has been critical of the administration's expanded use of prosecutorial discretion.

The study looked at the criminal records of people who were arrested by police, fingerprinted and brought to the attention of immigration officials through a controversial information-sharing program called Secure Communities. It found that between October 2008 and July 2011, 46,734 illegal immigrants were booked into jail but were released before immigration officials took them into custody.

"The idea that somehow ICE is knowingly taking people into custody who are removable and then releasing them is simply false," John Morton, the agency's director, said in an interview. "I strongly refute the Judiciary Committee's conclusions. It does a disservice to the facts."

Morton said ICE offices were sometimes far from the site of an arrest, or a person was arrested and booked on a minor charge and released within an hour, making it hard for immigration agents to respond in time.

"ICE cannot have a manned presence in every single state, local and county lock-up," he said.

Morton said Secure Communities was partly responsible for nearly doubling the number of deportations of convicted criminals and repeat immigration violators, from 114,415 in 2008 to 216,698 in 2011. The number of people deported from the U.S. has increased slightly every year since Obama took office.

Secure Communities, which links the FBI criminal database with immigration records, has met opposition from some police officials who fear it deters immigrants from reporting crimes and helping law enforcement.

But some experts consider Secure Communities an improvement over earlier programs that relied on police who had been deputized to enforce federal immigration law.

Secure Communities is used in 3,074 jurisdictions out of 3,181 nationwide — 97% of all state, local and tribal police departments. Alabama and Illinois are the only states where it is not in every police department.